The present invention relates generally to air cleaners or air filters and more specifically to air cleaners with cylindrical pleated paper filter elements which are used primarily on the over-the-road trucks and agricultural vehicles. Such applications generally are severe filtering environments.
U.S. Pat. No. 3,078,650 shows one prior art structure of air cleaner of this type. The air cleaner has a tubular metal housing with an inlet for dust laden air. A cylindrical pleated paper filter element is mounted within the housing. A clean air outlet communicates with the interior of the pleated paper filter element. A seal must be provided between the pleated paper element and the outlet so that the dust laden inlet air will be forced through the pleated paper media of the filter whereby particulates are removed from the air flow before it exits from the filter. In the '650 patent the seal between the filter element and the outlet is provided by a gasket secured to the filter element. The gasket engages an end wall of the tubular housing with the filter element held in place by a yoke and associated bolt and nut assembly.
U.S. Pat. No. 4,720,292 discloses another prior art structure for a cylindrical air filter of the type of the present invention. In its preferred embodiment, the housing of the '292 air filter is formed of a plastic material. A cylindrical pleated paper filter element is mounted within the housing. The pleated paper element has an open end for fluid communication with the air outlet. The open end of the filter element has a ring like end cap that is preferably made from an elastomer such as urethane foam which has a relatively soft, rubber-like consistency. The air filter element is mounted on the air outlet tube, and a seal is provided by engagement of the end cap with the tubular outlet member.
In order to manufacture an air filter using a plastic housing, a mold for the housing is typically needed. A separate mold would typically be used for housings that vary in size as well as variations in location of the air inlet. The tooling for molds for each possible application of the air filter can be quite expensive.